Aluminum alloy and preparation method thereof

ABSTRACT

An aluminum alloy and a preparation method thereof are provided. In percentage by mass, the aluminum alloy includes: 8-11% of Si, 2-3% of Cu, 0.7-1.1% of Mg, 0.7-1.5% of Mn, 0.01-0.015% of Sr, 0.01-0.015% of Cr, 0-0.4% of Fe, 0.02-0.1% of Ti, 0.01-0.02% of Ga, 0.004-0.02% of B, 0-2% of Zn, and the balance of Al and less than 0.1% of other elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is the U.S. National Stage Application of PCTInternational Application No. PCT/CN2020/081455, filed on Mar. 26, 2020,which claims priority to and benefits of Chinese Patent Application No.201911174477.0 filed on Nov. 26, 2019, which are incorporated herein byreference in their entireties.

FIELD

The present disclosure relates to the technical field of die-castingaluminum alloy, and more specifically, to an aluminum alloy and apreparation method thereof.

BACKGROUND

Die casting is a precision casting process that is characterized byforcing molten metal under high pressure into a metal mold cavity with acomplex shape. Die castings are characterized by a very smalldimensional tolerance and a high surface precision. In most cases, diecastings can be directly assembled for use without turning.

Die casting of aluminum alloys has high requirements on their mechanicalproperties, such as yield strength, tensile strength, elongation, andmelt fluidity. During die casting, existing die-casting aluminum alloymaterials are highly dependent on the accuracy of control conditions forthe formation process and are greatly affected by slight variation inprocess parameters, so that it is difficult to give consideration to therequirements of both the strength and elongation for die casting.

SUMMARY

To resolve the problem that it is difficult to give consideration toprocess requirements for existing die-casting aluminum alloy materials,the present disclosure discloses an aluminum alloy and a preparationmethod.

The technical solutions adopted by the present disclosure to resolve theforegoing technical problem are as follows:

According to an aspect, the present disclosure provides an aluminumalloy. In percentage by mass, the aluminum alloy includes: 8-11% of Si,2-3% of Cu, 0.7-1.1% of Mg, 0.7-1.5% of Mn, 0.01-0.015% of Sr,0.01-0.015% of Cr, 0-0.4% of Fe, 0.02-0.1% of Ti, 0.01-0.02% of Ga,0.004-0.02% of B, 0-2% of Zn, and the balance of Al and less than 0.1%of other elements.

In some embodiments, in percentage by mass, the aluminum alloy includes:9-10.8% of Si, 2.5-2.8% of Cu, 0.7-1.1% of Mg, 0.9-1.3% of Mn,0.01-0.015% of Sr, 0.01-0.015% of Cr, 0-0.4% of Fe, 0.03-0.1% of Ti,0.01-0.015% of Ga, 0.004-0.01% of B, 0-2% of Zn, and the balance of Aland less than 0.1% of other elements.

According to the aluminum alloy in some embodiments of the presentdisclosure, the mass ratio of Ti to B is (5-10):1.

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Ga in percentage by mass is greater than thecontent of Sr in percentage by mass.

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Si and the content of Cu satisfy thefollowing condition: Wt(Si)=(Wt(Cu)−0.2)×(3−5).

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Mn and the content of Cu satisfy thefollowing condition: Wt(Cu)=(Wt(Mn)−0.3)×(2.5−4).

According to the aluminum alloy in some embodiments of the presentdisclosure, the other elements include one or more of Zr, Ni, Ce, Sc,and Er.

According to another aspect, the present disclosure provides a methodfor preparing the foregoing aluminum alloy. The method includes thefollowing steps: weighing out various raw materials in requiredproportions based on proportions of all elements in the aluminum alloy,melting the raw materials in a melting furnace to obtain a molten metal,and subjecting the molten metal to slag removal and refining anddegassing, and then casting, to obtain an aluminum alloy ingot.

According to the method in some embodiments of the present disclosure,the slag removal includes adding a slag remover into the molten metal,the slag remover including one or more of an aluminum alloy slag removeragent NF-1 and an aluminum alloy slag-removal agent DSG.

According to the method in some embodiments of the present disclosure,the refining is carried out at 700-710° C., and the refining includesadding a refining agent into the molten metal, the refining agentincluding one or more of hexafluoroethane and an aluminum refining agentZS-AJ01C.

According to the method in some embodiments of the present disclosure,the method further includes die casting the aluminum alloy ingot forformation.

According to the method in some embodiments of the present disclosure,the method includes carrying out artificial aging on the die-castaluminum alloy.

According to the method in some embodiments of the present disclosure,the artificial aging is carried out at 100-200° C. for 1.5-3 h.

By adjusting proportions of all strengthening elements in the aluminumalloy, the aluminum alloy provided in the present disclosure has highyield strength and thermal conductivity, and ensures good elongationwithout sacrificing the strength. For the aluminum alloy in the presentdisclosure, the yield strength is about 240-260 MPa, the tensilestrength is about 380-410 MPa, the elongation is 3-6%, and the thermalconductivity is about 130-142 W/(k·m). In addition, the aluminum alloymaterial has low process requirements, and has good process adaptabilityin die casting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a metallographic image of an aluminum alloy prepared inExample 1 of the present disclosure;

FIG. 2 is an SEM image of an aluminum alloy prepared in Example 1 of thepresent disclosure; and

FIG. 3 is an SEM-diffraction spectrum of the area marked with the crossin FIG. 2 .

DETAILED DESCRIPTION

To make the technical problems to be resolved by the present disclosure,technical solutions, and beneficial effects more comprehensible, thefollowing further describes the present disclosure in detail withreference to the accompanying drawings and embodiments. It should beunderstood that the specific embodiments described herein are merelyused for explaining the present disclosure instead of limiting thepresent disclosure.

According to an aspect, the present disclosure provides an aluminumalloy. In percentage by mass, the aluminum alloy includes: 8-11% of Si,2-3% of Cu, 0.7-1.1% of Mg, 0.7-1.5% of Mn, 0.01-0.015% of Sr,0.01-0.015% of Cr, 0-0.4% of Fe, 0.02-0.1% of Ti, 0.01-0.02% of Ga,0.004-0.02% of B, 0-2% of Zn, and the balance of Al and less than 0.1%of other elements.

By adjusting proportions of all strengthening elements in the aluminumalloy, the aluminum alloy provided in the present disclosure has highyield strength and thermal conductivity, and ensures good elongationwithout sacrificing the strength. For the aluminum alloy in the presentdisclosure, the yield strength is about 240-260 MPa (for example, 240MPa, 242 MPa, 245 MPa, 248 MPa, 250 MPa, 251 MPa, 253 MPa, 255 MPa, 258MPa, or 260 MPa), the tensile strength is about 380-410 MPa (forexample, 380 MPa, 385 MPa, 390 MPa, 395 MPa, 400 MPa, 405 MPa, or 410MPa), the elongation is about 3-6% (for example, 3%, 3.5%, 4%, 4.5%, 5%,5.5%, or 6%), and the thermal conductivity is about 130-142 W/(k·m) (forexample, 130 W/(k·m), 132 W/(k·m), 135 W/(k·m), 138 W/(k·m), 140W/(k·m), or 142 W/(k·m)). In addition, the aluminum alloy material haslow process requirements, and has good process adaptability in diecasting.

In some embodiments, in percentage by mass, the aluminum alloy includes:9-10.8% of Si, 2.5-2.8% of Cu, 0.7-1.1% of Mg, 0.9-1.3% of Mn,0.01-0.015% of Sr, 0.01-0.015% of Cr, 0-0.4% of Fe, 0.03-0.1% of Ti,0.01-0.015% of Ga, 0.004-0.01% of B, 0-2% of Zn, and the balance of Aland less than 0.1% of other elements.

In some other embodiments, the aluminum alloy is composed of thefollowing components in percentage by mass: 9-10.8% of Si, 2.5-2.8% ofCu, 0.7-1.1% of Mg, 0.9-1.3% of Mn, 0.01-0.015% of Sr, 0.01-0.015% ofCr, 0-0.4% of Fe, 0.03-0.1% of Ti, 0.01-0.015% of Ga, 0.004-0.01% of B,0-2% of Zn, and the balance of Al.

In some embodiments, the content of Si is 9%, 9.8%, 10%, 10.5%, or10.8%, the content of Cu is 2.5%, 2.6%, or 2.8%, the content of Mg is0.7%, 0.8%, 0.9%, 1%, or 1.1%, the content of Mn is 0.9%, 1%, 1.1%,1.2%, or 1.3%, the content of Sr is 0.01%, 0.013%, 0.015%, or 0.02%, thecontent of Cr is 0.01%, 0.013%, or 0.015%, the content of Fe is 0, 0.1%,0.2%, 0.3%, or 0.4%, the content of Ti is 0.03%, 0.04%, 0.05%, or 0.06%,the content of Ga is 0.01%, 0.013%, or 0.015%, the content of B is0.004%, 0.005%, 0.006%, 0.007%, or 0.008%, and the content of Zn is 0,0.3%, 0.6%, 0.9%, 1.3%, 1.7%, or 2%.

In the materials involved in the present disclosure, Si and Al formeutectic Si and primary Si. Dispersed primary Si and fine α-Al grainsare formed under the effect of Sr, increasing the strength and fluidityof the aluminum alloy.

According to the aluminum alloy in some embodiments of the presentdisclosure, Cu is solubilized into Al to form a solid solution phase,and precipitated Al₂Cu strengthening phase is dispersed on the grainboundary.

According to the aluminum alloy in some embodiments of the presentdisclosure, with the increase of Mg content, the yield strengthincreases and the elongation decreases gradually. When the Mg content ismore than 0.7%, a dispersion strengthening phase (with a particle sizebelow 10 μm) mainly composed of Al₂Cu is precipitated. With the increaseof the Mg content, the area occupied by this phase in the aluminum alloygradually increases. When the Mg content is more than 1.1%, the grainsof this phase in the aluminum alloy will increase sharply, and theelongation will decrease greatly.

According to the aluminum alloy in some embodiments of the presentdisclosure, Mn and Cr are solubilized into the aluminum alloy matrix toinhibit the grain growth of primary Si and α-Al, so that the primary Siis dispersed among grains.

According to the aluminum alloy in some embodiments of the presentdisclosure, Ti and B are dispersed among the grains, so that primary Sican uniformly distribute into α-Al, which greatly inhibits the growth ofα-Al (the particle size of α-Al is reduced by one-third compared withthat in the aluminum alloy without the addition of Ti and B).

According to the aluminum alloy in some embodiments of the presentdisclosure, an excessively high content of Zn is easily solubilized intothe aluminum alloy, thereby affecting the solubilization of Cu, Mn, andMg, which will affect the precipitated second phase and greatly changethe thermal conductivity of the aluminum alloy.

According to the aluminum alloy in some embodiments of the presentdisclosure, an excessively high content of Fe will make the aluminumalloy brittle and thus affect the elongation of the aluminum alloy.

The mechanical properties, thermal conductivity, and elongation of thealuminum alloy are the result of the combined effect of the foregoingelements. Any element that deviates from the scope provided by thepresent disclosure deviates from the disclosure intent of the presentdisclosure, resulting in a reduction in mechanical properties, thermalconductivity, or elongation of the aluminum alloy, thereby detrimentalto the use of the aluminum alloy as a die-casting material.

According to the aluminum alloy in some embodiments of the presentdisclosure, the mass ratio of Ti to B is (5-10):1, for example 5:1, 6:1,7:1, 8:1, 9:1, or 10:1. It was found through further experiments that Tiand B in this ratio ensure the high strength and thermal conductivity ofthe aluminum alloy. The reason is that Ti within this content range isuniformly distributed around the eutectic Si, increasing the strength ofthe aluminum alloy, and the addition of B in this ratio ensures the highstrength with good thermal conductivity.

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Ga in percentage by mass is greater than thecontent of Sr in percentage by mass.

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Si and the content of Cu satisfy thefollowing condition: Wt(Si)=(Wt(Cu)−0.2)×(3−5). Under this condition,the formed eutectic Si and Al₂Cu inhibit the growth of the α-Al grains,which become small in diameter.

According to the aluminum alloy in some embodiments of the presentdisclosure, the content of Mn and the content of Cu satisfy thefollowing condition: Wt(Cu)=(Wt(Mn)−0.3)×(2.5−4). Under this condition,through the induction of Ti—B, Si, Cu, and Mn form a new sphericalSi₇Mn₆Cu phase uniformly distributed at the grain boundary, greatlyincreasing the strength and elongation of the aluminum alloy.

Under the foregoing conditions, a high-strength a solid solution isformed in the aluminum alloy. In this case, Ti, Ga, and B form a finestrengthening phase evenly distributed between the eutectic Si and asolid solution, which greatly increases the yield strength of thealuminum alloy while ensuring the elongation of the aluminum alloy.

According to the aluminum alloy in some embodiments of the presentdisclosure, the other elements include one or more of Zr, Ni, Ce, Sc,and Er. Zr, Ni, Ce, Sc, and Er are harmful elements that need to bereduced as impurities from the aluminum alloy as much as possible. Insome specific embodiments, the aluminum alloy does not include the otherelements.

For example, as an impurity element, the solubilization of Ni into asolid solution of the alloy will have a greater impact on Cu, Mn, andMg, resulting in severe segregation, thereby making the aluminum alloybrittle. Zr, Ce, Er, and Sc form a second phase that cannot besolubilized in the aluminum alloy, so that the distribution ofcomposition of the aluminum alloy is uneven, making the aluminum alloybrittle.

According to another aspect, the present disclosure provides a methodfor preparing the foregoing aluminum alloy. The method includes thefollowing steps: weighing out various raw materials in requiredproportions based on proportions of all elements in the aluminum alloy,melting the raw materials in a melting furnace to obtain a molten metal,and subjecting the molten metal to slag removal and refining anddegassing, and then casting, to obtain an aluminum alloy ingot. The rawmaterials include an Al-containing material, a Si-containing material, aMg-containing material, a Fe-containing material, a Sr-containingmaterial, a Ti-containing material, a B-containing material, aCu-containing material, a Mn-containing material, a Ga-containingmaterial, a Cr-containing material, and a Zn-containing material. Theraw materials are selected from alloys or elements containing theforegoing elements.

In some embodiments, the slag removal includes adding a slag removerinto the molten metal, the slag remover including one or more of analuminum alloy slag remover agent NF-1 and an aluminum alloyslag-removal agent DSG.

In some embodiments, the refining is carried out at 700-710° C.(specifically 700° C., 701° C., 702° C., 703° C., 704° C., 705° C., 706°C., 707° C., 708° C., 709° C., or 710° C.). The refining includes addinga refining agent into the molten metal and stirring. The refining agentincludes one or more of hexafluoroethane and an aluminum refining agentZS-AJ01C.

According to the method in some embodiments of the present disclosure,the method further includes die casting the aluminum alloy ingot forformation.

In some embodiments, the casting is carried out at 680-720° C. (forexample 680° C., 690° C., 700° C., 710° C., or 720° C.).

In some embodiments, artificial aging is carried out on the die-castaluminum alloy at 100-200° C. (for example 100° C., 110° C., 120° C.,130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 190° C., or 200°C.) for 1.5-3 h (for example 1.5 h, 2 h, 2.5 h, or 3 h).

The aluminum alloy is precipitation-hardened by the artificial aging,and the precipitation hardening effect can be observed by testing themechanical properties of the aluminum alloy. The precipitation of Al₂Cuphase is accelerated at 100-200° C., increasing the strength of thegrain boundary, thereby increasing the strength and hardness of thealloy.

The present disclosure is further described through the followingexamples.

TABLE 1 Inevitable impurities Si Cu Mn Mg Ti Sr Cr Fe Ga B Zn and AlExample 1 9.5 2.7 1.2 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 2 102.7 1.2 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 3 10.5 2.7 1.2 1 0.040.013 0.012 0 0.014 0.005 0 Example 4 10 2.5 1.2 1 0.04 0.013 0.012 00.014 0.005 0 Example 5 10 2.6 1.2 1 0.04 0.013 0.012 0 0.014 0.005 0Example 6 10 2.8 1.2 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 7 10 2.50.9 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 9 10 2.5 1.1 1 0.04 0.0130.012 0 0.014 0.005 0 Example 10 10 2.5 1.2 1 0.04 0.013 0.012 0 0.0140.005 0 Example 11 10.5 2.5 0.95 0.8 0.04 0.013 0.012 0 0.014 0.005 0Example 12 10.5 2.5 1 0.9 0.04 0.013 0.012 0 0.014 0.005 0 Example 1310.5 2.5 0.95 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 14 10.5 2.5 1.10.8 0.03 0.013 0.012 0 0.014 0.004 0 Example 15 10.5 2.5 1.1 0.8 0.070.013 0.012 0 0.014 0.005 0 Example 16 10.5 2.5 1.1 0.8 0.08 0.013 0.0120 0.014 0.005 0 Example 17 10.5 2.5 1.1 0.8 0.05 0.013 0.012 0 0.0140.005 0 Example 18 10.5 2.5 1.1 0.8 0.03 0.013 0.012 0 0.014 0.005 0Example 19 10.5 2.5 1.1 0.8 0.03 0.013 0.01 0 0.014 0.005 0 Example 2010.5 2.5 1.1 0.8 0.03 0.013 0.015 0.1 0.014 0.005 0 Example 21 10.5 2.51.1 0.8 0.05 0.013 0.012 0.2 0.014 0.005 0.5 Example 22 10.5 2.5 1.1 0.80.05 0.013 0.012 0.3 0.014 0.005 1 Example 23 8.5 2.7 1.2 1 0.04 0.0130.012 0 0.014 0.005 0 Example 24 10 2.2 1.2 1 0.04 0.013 0.012 0 0.0140.005 0 Example 25 10 2.8 1.4 1 0.04 0.013 0.012 0 0.014 0.005 0 Example27 10.5 2.5 1.1 0.8 0.03 0.015 0.012 0 0.02 0.005 0 Example 28 10.5 2.51.1 1 0.02 0.013 0.012 0 0.014 0.005 0 Example 29 10.5 2.5 1.1 1 0.10.013 0.012 0 0.014 0.005 0 Example 30 10.5 2.5 1.1 1 0.04 0.013 0.012 00.01 0.005 0 Example 31 10.5 2 1.1 1 0.04 0.013 0.012 0 0.014 0.005 0Example 32 8 3 1.1 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 33 10.52.5 0.8 1 0.04 0.013 0.012 0 0.014 0.005 0 Example 34 10.5 2.5 1.5 10.04 0.013 0.012 0 0.014 0.005 0 Comparative 7.8 2.7 1.2 1 0.04 0.0130.012 0 0.014 0.005 0 Example 1 Comparative 12 2.7 1.2 1 0.04 0.0130.012 0 0.014 0.005 0 Example 2 Comparative 10 1.8 1.2 1 0.04 0.0130.012 0 0.014 0.005 0 Example 3 Comparative 10 3.5 1.2 1 0.04 0.0130.012 0 0.014 0.005 0 Example 4 Comparative 10 2.5 0.5 1 0.04 0.0130.012 0 0.014 0.005 0 Example 5 Comparative 10 2.5 2 1 0.04 0.013 0.0120 0.014 0.005 0 Example 6 Comparative 10 2.5 1 1 0.04 0.013 0.012 0 00.005 0 Example 7 Comparative 10.5 2.5 1 0.5 0.04 0.013 0.012 0 0.0140.005 0 Example 8 Comparative 10.5 2.5 1 1.5 0.04 0.013 0.012 0 0.0140.005 0 Example 9 Comparative 10.5 2.5 1 0.7 0.15 0.013 0.012 0 0.0140.005 0 Example 10 Comparative 10.5 2.5 1 0.7 0.03 0.005 0.012 0 0.010.005 0 Examnle 11 Comparative 10.5 2.5 1 0.7 0.03 0.013 0 0 0.014 0.0050 Example 12 Comparative 10.5 2.5 1.1 0.7 0.05 0.013 0.012 0 0.014 0.0052.3 Example 13 Note: Each composition in Table is in percentage byweight, and the total weight of inevitable impurity elements is lessthan 0.1%.

Example 1

This example is used to describe the aluminum alloy and the preparationmethod thereof in the present disclosure, including the following steps:

As shown in Table 1, the components of the aluminum alloy in percentageby mass include: 9.5% of Si, 2.7% of Cu, 1% of Mg, 1.2% of Mn, 0.013% ofSr, 0.012% of Cr, 0% of Fe, 0.04% of Ti, 0.014% of Ga, 0.005% of B, 0%of Zn, and the balance of Al and less than 0.1% of inevitableimpurities. The required mass of intermediate alloys or metal elementswas calculated based on the mass of the foregoing components of thealuminum alloy, the intermediate alloys or metal elements were melted ina melting furnace to obtain a molten metal, and the molten metal wassubjected to slag removal by using a slag remover and was subjected torefining and degassing by using a refining agent at 700-710° C., andthen was cast to obtain an aluminum alloy ingot. The aluminum alloyingot was naturally aged for 7 d to obtain an aluminum alloy.

Examples 2-34

Examples 2-34 are used to describe the aluminum alloy and thepreparation method thereof in the present disclosure, including most ofthe steps in Example 1, and the difference is as follows:

The compositions of the aluminum alloy in Examples 2-34 are shown inTable 1, the required mass of intermediate alloys or metal elements wascalculated based on the mass of the foregoing components of the aluminumalloy, the intermediate alloys or metal elements were melted in amelting furnace to obtain a molten metal, and the molten metal wassubjected to slag removal by using a slag remover and was subjected torefining and degassing by using a refining agent at 700-710° C., andthen was cast to obtain an aluminum alloy ingot. The aluminum alloyingot was naturally aged for 7 d to obtain an aluminum alloy.

Comparative Example 1

This comparative example is used to compare with the aluminum alloy andthe preparation method thereof in the present disclosure, including thefollowing steps:

As shown in Table 1, the components of the aluminum alloy in percentageby mass include: 7.8% of Si, 2.7% of Cu, 1% of Mg, 1.2% of Mn, 0.013% ofSr, 0.012% of Cr, 0% of Fe, 0.04% of Ti, 0.014% of Ga, 0.005% of B, 0%of Zn, and the balance of Al and less than 0.1% of inevitableimpurities. The required mass of intermediate alloys or metal elementswas calculated based on the mass of the foregoing components of thealuminum alloy, the intermediate alloys or metal elements were melted ina melting furnace to obtain a molten metal, and the molten metal wassubjected to slag removal by using a slag remover and was subjected torefining and degassing by using a refining agent at 700-710° C., andthen was cast to obtain an aluminum alloy ingot. The aluminum alloyingot was naturally aged for 7 d to obtain an aluminum alloy.

Comparative Examples 2-13

Comparative Examples 2-13 are used to compare with the aluminum alloyand the preparation method thereof in the present disclosure, includingmost of the steps in Example 1, and the difference is as follows:

The compositions of the aluminum alloy in Comparative Examples 2-13 areshown in Table 1, the required mass of intermediate alloys or metalelements was calculated based on the mass of the foregoing components ofthe aluminum alloy, the intermediate alloys or metal elements weremelted in a melting furnace to obtain a molten metal, and the moltenmetal was subjected to slag removal by using a slag remover and wassubjected to refining and degassing by using a refining agent at700-710° C., and then was cast to obtain an aluminum alloy ingot. Thealuminum alloy ingot was naturally aged for 7 d to obtain an aluminumalloy.

Performance Test

The aluminum alloy prepared in Example 1 was imaged by using a scanningelectron microscope (SEM) to obtain SEM images shown in FIG. 1 and FIG.2 . The area marked with the cross in FIG. 2 was subjected todiffraction to obtain an SEM-diffraction spectrum shown in FIG. 3 . TheEDS spectrum was analyzed to obtain the composition of the area markedwith the cross in FIG. 2 , as shown in Table 2.

TABLE 2 Element wt % at % CK 02.52 05.94 OK 01.42 02.52 MgK 00.81 00.95AlK 71.05 74.60 SiK 07.69 07.76 MnK 12.40 06.39 CuK 04.11 01.83 MatrixCorrection ZAF

It can be learned that a spherical Si₇Mn₆Cu phase is formed herein inFIG. 2 and is evenly distributed at the grain boundary, increasing thestrength and elongation of the aluminum alloy.

The aluminum alloys prepared in Examples 1-34 and Comparative Examples1-13 were subjected to the following performance tests:

Tensile test: The yield strength, tensile strength, and elongation weretested according to GBT 228.1-2010 Metallic Materials Tensile TestingPart 1: Room Temperature Test Methods.

Thermal conductivity test: A thermally conductive ingot wafer of ϕ12.7×3 mm was prepared as a to-be-tested piece, and graphite was evenlysprayed on both sides of the to-be-tested piece to form a coating. Thecoated piece was tested by using a laser thermal conductivityinstrument. The laser thermal conductivity test was carried out inaccordance with ASTM E1461 Standard Test Method for Thermal Diffusivityby the Flash Method.

The test results are shown in Table 3.

TABLE 3 Thermal Yield Tensile conductivity strength strength ElongationDie-casting of ingot (MPa) (MPa) (%) formability W/(m · k) Example 1 243415 5.12 Excellent 137 Example 2 251 418 4.83 Excellent 138 Example 3255 411 4.53 Excellent 135 Example 4 248 410 4.54 Excellent 132 Example5 249 413 4.2 Excellent 134 Example 6 252 410 4.48 Excellent 133 Example7 248 412 4.52 Excellent 138 Example 8 249 418 5.03 Excellent 136Example 9 251 417 4.93 Excellent 134 Example 10 253 418 4.28 Excellent132 Example 11 243 418 5.21 Excellent 138 Example 12 249 418 5.02Excellent 136 Example 13 254 415 4.35 Excellent 135 Example 14 245 4134.2 Excellent 135 Example 15 251 410 4.35 Excellent 133 Example 16 250407 4.38 Excellent 135 Example 17 251 421 5.02 Excellent 133 Example 18245 411 4.82 Excellent 138 Example 19 245 410 4.53 Excellent 136 Example20 245 413 4.82 Excellent 135 Example 21 247 412 4.35 Excellent 133Example 22 252 410 4.32 Excellent 132 Example 23 242 403 4.5 Good 135Example 24 241 405 4.68 Good 136 Example 25 252 401 3.52 Good 130Example 26 242 398 4.25 Excellent 137 Example 27 243 405 4.52 Excellent134 Example 28 241 403 4.32 Excellent 132 Example 29 241 405 4.35Excellent 130 Example 30 251 395 3.8 Excellent 131 Example 31 242 3953.2 Excellent 131 Example 32 241 385 3.1 Good 131 Example 33 241 3863.92 Good 132 Example 34 252 392 3.53 Excellent 130 Comparative 241 3732.8 Average 121 Example 1 Comparative 252 382 2.3 Good 118 Example 2Comparative 235 375 3.1 Good 118 Example 3 Comparative 252 379 2.23Average 115 Example 4 Comparative 235 381 2.82 Average 127 Example 5Comparative 261 370 2.31 Average 115 Example 6 Comparative 241 373 2.85Good 123 Example 7 Comparative 223 372 3.5 Good 135 Example 8Comparative 261 371 2.22 Average 115 Example 9 Comparative 236 370 3.38Good 121 Example 10 Comparative 238 372 3.26 Good 123 Example 11Comparative 237 369 3.17 Good 125 Example 12 Comparative 237 372 3.18Good 123 Example 13

It can be learned by comparing the test results of Examples 1-34 withthe test results of Comparative Examples 1-13 that, the mechanicalstrength, thermal conductivity, elongation, and die-casting formabilityof the aluminum alloy provided in the present disclosure is better thanthe aluminum alloys beyond the element range provided in the presentdisclosure. And the aluminum alloy provided in the present disclosurecan meet the requirements of the die-casting process.

The foregoing descriptions are merely embodiments of the presentdisclosure, but are not intended to limit the present disclosure. Anymodification, equivalent replacement, or improvement made within thespirit and principle of the present disclosure shall fall within theprotection scope of the present disclosure.

What is claimed is:
 1. An aluminum alloy, in percentage by mass, thealuminum alloy comprising: 8-11% of Si, 2-3% of Cu, 0.7-1.1% of Mg,0.7-1.5% of Mn, 0.01-0.015% of Sr, 0.01-0.015% of Cr, 0-0.4% of Fe,0.02-0.1% of Ti, 0.01-0.02% of Ga, 0.004-0.02% of B, 0-2% of Zn, and thebalance of Al and less than 0.1% of other elements.
 2. The aluminumalloy according to claim 1, in percentage by mass, the aluminum alloycomprising: 9-10.8% of Si, 2.5-2.8% of Cu, 0.7-1.1% of Mg, 0.9-1.3% ofMn, 0.01-0.015% of Sr, 0.01-0.015% of Cr, 0-0.4% of Fe, 0.03-0.1% of Ti,0.01-0.015% of Ga, 0.004-0.01% of B, 0-2% of Zn, and the balance of Aland less than 0.1% of other elements.
 3. The aluminum alloy according toclaim 1, wherein a mass ratio of Ti to B is (5-10):1.
 4. The aluminumalloy according to claim 1, wherein a content of Ga in percentage bymass is greater than a content of Sr in percentage by mass.
 5. Thealuminum alloy according to claim 1, wherein a content of Si and acontent of Cu satisfy the following condition:Wt(Si)=(Wt(Cu)−0.2)×(3−5).
 6. The aluminum alloy according to claim 1,wherein a content of Mn and a content of Cu satisfy the followingcondition:Wt(Cu)=(Wt(Mn)−0.3)×(2.5−4).
 7. The aluminum alloy according to claim 1,wherein the other elements comprise one or more of Zr, Ni, Ce, Sc, andEr.
 8. A method for preparing the aluminum alloy according to claim 1,comprising the following steps: weighing out various raw materials inrequired proportions based on proportions of all elements in thealuminum alloy, melting the raw materials in a melting furnace to obtaina molten metal, and subjecting the molten metal to slag removal andrefining and degassing, and then casting, to obtain an aluminum alloyingot.
 9. The method according to claim 8, wherein the slag removalcomprises adding a slag remover into the molten metal, the slag removercomprising one or more of an aluminum alloy slag remover agent NF-1 andan aluminum alloy slag-removal agent DSG.
 10. The method according toclaim 8, wherein the refining is carried out at 700-710° C., and therefining comprises adding a refining agent into the molten metal, therefining agent comprising one or more of hexafluoroethane and analuminum refining agent ZS-AJ01C.
 11. The method according to claim 8,further comprising: die casting the aluminum alloy ingot for formation.12. The method according to claim 11, comprising carrying out artificialaging on the die-cast aluminum alloy.
 13. The method according to claim12, wherein the artificial aging is carried out at 100-200° C. for 1.5-3h.